System and method for detecting motion of a body

ABSTRACT

The present invention comprises a system and method for detecting an acceleration of a body and for evaluating movement of a body relative to an environment to detect falls and irregular motions of the body. According to an exemplary embodiment, the system comprises a sensor and a controller that comprises a processor. The sensor, which is associable with the body, comprises a plurality of acceleration measuring devices and is capable of repeatedly sensing accelerative phenomena of the body. The controller, which is associated with the sensor, is operable to process the sensed accelerative phenomena as a function of at least one accelerative event characteristic. The controller determines when the body experiences an acceleration that represents a particular type of motion. The controller also determines when a static acceleration vector reaches a value indicative of a fall. After a fall has occurred, the controller is capable of determining whether the controller was connected to a body during the fall or whether only the controller experienced the fall.

RELATED APPLICATIONS

This patent application is a continuation in part of co-pending U.S.patent application Ser. No. 09/396,991 filed Sep. 15, 1999 by Lehrman etal. entitled “Systems For Evaluating Movement of A Body and Methods ofOperating The Same.” This patent application is also related to U.S.Provisional Patent Application No. 60/265,521 filed Jan. 31, 2001 byLehrman et al. entitled “System and Method for Detecting an Accelerationof a Body.” U.S. patent application Ser. No. 09/396,991 and U.S.Provisional Patent Application No. 60/265,521 are both assigned to theassignee of the present invention. The disclosures in U.S. patentapplication Ser. No. 09/396,991 and in U.S. Provisional PatentApplication No. 60/265,521 are hereby incorporated by reference in thepresent application as if fully set forth herein.

TECHNICAL FIELD OF THE INVENTION

The present invention relates generally to means for detecting motionsof a body, and, more particularly, relates to systems and methods ofoperation thereof, for evaluating movement of a body relative to anenvironment to identify occurrences of irregular body motions or falls.

BACKGROUND OF THE INVENTION

Methods for determining specific movements of a body that use a varietyof devices, apparatus and systems are, generally speaking, known. Theterm “body” is defined broadly hereafter and includes both organic andinorganic objects.

In point of fact, many methods are known for sensing body movement, ornon-movement (i.e., sensed dynamic accelerations, including cessation ofmovement), as well as, for sensing body movement over time, which iscommonly used to determine comparative levels of activity of a monitoredbody (See, U.S. Pat. Nos. 4,110,741, 4,292,630, 5,045,839, and5,523,742). These methodologies, however, merely report various levelsof body activity, and, simply stated, fail to recognize possible causesfor any increased or decreased level of body activity.

In contrast, other methodologies have developed over time for thedetection of falls (See also, U.S. Pat. Nos. 4,829,285, 5,477,211,5,554,975, and 5,751,214). These methodologies are largely based uponthe utilization of one or more mechanical switches (e.g., mercuryswitches) that determine when a body has attained a horizontal position.These methods however fail to discern “normal,” or acceptable, changesin levels of body activity. Stated another way, the foregoing falldetection methodologies provide no position change analysis and,therefore, cannot determine whether a change in position, once attained,is acceptable or unacceptable.

Various training methods have been conceived for sensing relative tiltof a body (See, U.S. Pat. Nos. 5,300,921 and 5,430,435), and some suchmethodologies have employed two-axis accelerometers. The output of thesedevices, however, have reported only static acceleration of the body(i.e., the position of a body relative to earth within broad limits). Itshould be appreciated that static acceleration, or gravity, is not thesame as a lack of dynamic acceleration (i.e., vibration, body movement,and the like), but is instead a gauge of position. While accelerometersthat measure both static and dynamic acceleration are known, theirprimary use has heretofore been substantially confined to applicationsdirected to measuring one or the other, but not both.

Thus, it may be seen that the various conventional detectors fall intoone of two varieties, those that gauge movement of the body and thosethat gauge a body's position by various means, with neither type capableof evaluating body movement to determine whether the same is normal orabnormal; and if abnormal, whether such movement is so abnormal to bebeyond tolerance, for instance, to be damaging, destructive, crippling,harmful, injurious, or otherwise alarming or, possibly, distressing tothe body. None of the methodologies heretofore known have provided asuitable means to evaluate body movement over time and to determinewhether such movement is tolerable. Further improvement could thus beutilized.

SUMMARY OF THE INVENTION

To address the above-introduced deficiencies of the prior art, thepresent invention introduces systems, as well as methods of operatingsuch systems, for evaluating movement of a body relative to anenvironment. For the purposes hereof, the term “body” is definedbroadly, meaning any organic or inorganic object whose movement orposition may suitably be evaluated relative to its environment inaccordance with the principles hereof; and where the term “environment”is defined broadly as the conditions and the influences that determinethe behavior of the physical system in which the body is located.

An advantageous embodiment of a system that evaluates movement of a bodyrelative to an environment in accordance herewith includes both a sensorand a processor. In operation, the sensor is associated with the bodyand operates to repeatedly sense accelerative phenomena of the body. Theprocessor, which is associated with the sensor, processes the sensedaccelerative phenomena as a function of at least one accelerative eventcharacteristic to determine whether the evaluated body movement iswithin environmental tolerance. The processor also preferably generatesstate indicia while processing the sensed accelerative phenomena, whichrepresents the state of the body within the environment over time.

For the purposes hereof, the term “sensor” is defined broadly, meaning adevice that senses one or more absolute values, changes in value, orsome combination of the same, of at least the sensed accelerativephenomena. According to an advantageous embodiment, described in detailhereafter, the sensor may be a plural-axis sensor that sensesaccelerative phenomena and generates an output signal to the processorindicative of measurements of both dynamic and static acceleration ofthe body in plural axes.

According to this embodiment, the processor receives and processes theoutput signal. The processor is preferably programmed to distinguishbetween normal and abnormal accelerative events, and, when an abnormalevent is identified, to indicate whether the abnormal event istolerable, or within tolerance. In further embodiments, the processormay be programmed to distinguish other physical characteristics,including temperature, pressure, force, sound, light, relative position,and the like.

It should be noted that the relevant environment may be statically ordynamically represented. The sophistication of any such representationmay be as complex or as uncomplicated as needed by a given application(e.g., disability, injury, infirmity, relative position, or otherorganic assistance monitoring; cargo or other transport monitoring;military, paramilitary, or other tactical maneuver monitoring; etc.). Itshould further be noted that any representation may initially be set to,or reset to, a default, including, for instance, a physically emptyspace, or vacuum.

Regardless, the principles of the advantageous exemplary embodimentdiscussed heretofore require at least one accelerative eventcharacteristic to be represented to enable the processor to determinewhether the evaluated body movement is within environmental tolerance,which is again advantageously based upon both dynamic and staticacceleration measurements.

According to a related embodiment, the processor is further operable, inresponse to processing the sensed accelerative phenomena, to generatestate indicia, which includes tolerance indicia, generated in responseto determining whether the evaluated body movement is withinenvironmental tolerance. Preferably, such tolerance indicia is comparedwith at least one threshold, likely associated with the accelerativeevent characteristic. In response to such comparison, the processorcontrols a suitable indicating means to initiate an alarm event; tocommunicate such tolerance indicia to a monitoring controller; togenerate statistics; or the like.

According to a related advantageous embodiment, the system may beassociated with other components or sensing systems. For instance, in anassistance monitoring application, the sensor may repeatedly sensedynamic and static acceleration of the body in the plural axes andgenerate output signals indicative of the measurements. The processorcontinuously processes the output signals to distinguish betweenselected accelerative and non-selected accelerative events (described indetail hereafter) based upon both the dynamic and the staticacceleration of the body, and generates state indicia, includingtolerance indicia, that is communicated to a remote monitoringcontroller. The tolerance indicia is communicated to the monitoringcontroller for record keeping/statistical purposes, as well as toprovide “live” monitoring of the individual subscriber.

Communication between the processor and the controller may be by awireless network, a wired network, or some suitable combination of thesame, and may include the Internet. Preferably, the system generates analert whenever the monitored subscriber is in “jeopardy,” as determinedby the system, such as in response to a debilitating fall by thesubscriber. In a further embodiment, the processor is operable torepeatedly generate “heartbeat” indicia that indicates that the systemis in an operable state, whereby absence of the same informs themonitoring controller that some other part of the system ismalfunctioning.

The foregoing has outlined rather broadly the features and technicaladvantages of the present invention so that those skilled in the art maybetter understand the DETAILED DESCRIPTION OF THE INVENTION thatfollows. Additional features and advantages of the invention will bedescribed hereinafter that form the subject of the claims of theinvention. Those skilled in the art should appreciate that they mayreadily use the conception and specific embodiments disclosed as a basisfor modifying or designing other structures for carrying out the samepurposes of the present invention. Those skilled in the art should alsorealize that such equivalent constructions do not depart from the spiritand scope of the invention in its broadest form.

Before undertaking the DETAILED DESCRIPTION OF THE INVENTION, it may beadvantageous to set forth definitions of certain words and phrases usedthroughout this patent document: the terms “include” and “comprise,” aswell as derivatives thereof, mean inclusion without limitation; the term“or,” is inclusive, meaning and/or; the phrases “associated with” and“associated therewith,” as well as derivatives thereof, and the term“associable” may mean to include, be included within, interconnect with,contain, be contained within, connect to or with, couple to or with, becommunicable with, cooperate with, interleave, juxtapose, be proximateto, be bound to or with, have, have a property of, or the like; and theterms “controller” and “processor” mean any device, system or partthereof that controls at least one operation, such a device may beimplemented in hardware, firmware or software, or some suitablecombination of at least two of the same. It should be noted that thefunctionality associated with any particular controller/processor may becentralized or distributed, whether locally or remotely. Definitions forcertain words and phrases are provided throughout this patent document,those of ordinary skill in the art should understand that in many, ifnot most instances, such definitions apply to prior, as well as futureuses of such defined words and phrases.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention, and theadvantages thereof, reference is now made to the following descriptionstaken in conjunction with the accompanying drawings, wherein likenumbers designate like objects, and in which:

FIG. 1 illustrates an isometric view of an exemplary embodiment of asystem that evaluates body movement in accordance with the principles ofthe present invention;

FIG. 2 illustrates a block diagram of the exemplary system set forthwith respect to FIG. 1;

FIGS. 3A to 3D illustrate exemplary strip chart records of output of thesensor introduced in FIGS. 1 and 2 taken during illustrative situations;

FIG. 4 illustrates an operational flow diagram of an exemplary method ofprogramming a processor in accordance with a fall detection applicationof the principles of the present invention;

FIG. 5 illustrates a functional block diagram of an alternate sensingsystem that may suitably be associated with the processor of the presentinvention;

FIG. 6 illustrates a perspective view of an exemplary remote receiverunit of the system of this invention;

FIG. 7 illustrates a functional block diagram of the exemplary receiverunit of FIG. 6;

FIG. 8 illustrates an exemplary wireless network that is associated viaa wired network, such as the Internet, to a remote monitoring controlleraccording to one embodiment of the present invention; and

FIG. 9 illustrates an exemplary embodiment of the system of the presentinvention for evaluating body movement with a plurality of accelerationmeasuring devices;

FIG. 10 illustrates the coordinate relationships between a threedimensional Cartesian coordinate system and a three dimensionalspherical polar coordinate system;

FIG. 11 illustrates the orientation of a first plural axis accelerometerin an x-y plane of a three dimensional Cartesian coordinate system andthe orientation of a second plural axis accelerometer in a y-z plane ofthe same Cartesian coordinate system;

FIG. 12 illustrates an exemplary embodiment of the system of the presentinvention for evaluating body movement comprising two plural axisaccelerometer sensors coupled to a controller;

FIG. 13 illustrates a flow diagram showing a first portion of anadvantageous embodiment of the method of the present invention; and

FIG. 14 illustrates a flow diagram showing a second portion of anadvantageous embodiment of the method of the present invention.

DESCRIPTION OF THE INVENTION

FIGS. 1 through 14, discussed below, and the various embodiments used todescribe the principles of the present invention in this patent documentare by way of illustration only and should not be construed in any wayto limit the scope of the invention. Those skilled in the art willunderstand that the principles of the present invention may beimplemented in any suitably arranged system for detecting the motion ofa body.

FIG. 1 illustrates an isometric view of an exemplary embodiment of asystem (generally designated 11) that evaluates body movement inaccordance with the principles of the present invention, and moreparticularly that measures and distinguishes selected accelerativeevents of a body (not shown). As used in this disclosure, the phrases“accelerative events” or “accelerative phenomena” are defined asoccurrences of change in velocity of the body (or acceleration), whetherin magnitude, direction or both.

System 11 includes circuit boards 13 and 15 (connected boards at rightangles to one another) that are associated with a housing (generallydesignated 17) utilizing known mounting techniques. Exemplary housing 17(and system 11, for that matter), when assembled, is approximately onecentimeter thick and is approximately five centimeters across in anydirection.

Housing 17 may comprise, for example, exemplary housing halves 19 and 21that encase boards 13 and 15, although those skilled in the art willunderstand that any configuration suitable for a particularimplementation of the invention may be arranged.

Exemplary rear half 21 is provided with a clip 23 for associating system11 with the body (e.g., people, animals, objects of various sorts,etc.). Exemplary clip 23 is shown as a mechanical spring-type clip, butcould be any known attachment device or system, including eithermechanical or chemical attachment systems, or any other suitable meansfor associating system 11 with the body.

System 11 includes a processor (shown in FIG. 2) and a sensor 25.Exemplary sensor 25 operates to sense accelerative phenomena of thebody, and is mounted on circuit board 13 with x and y axes, 27 and 29,respectively, oriented thereat (though other orientations could beutilized).

Sensor 25 is illustratively shown as a plural-axis (dual shown)acceleration measuring device suitably mounted on a single monolithicintegrated circuit (one conventional sensor is an accelerometeravailable from ANALOG DEVICES, INC., located at One Technology Way,Norwood, Mass., United States of America, namely, Model No. ADXL202).Sensor 25 includes polysilicon surface-micromachined sensor layer 31built on top of silicon wafer 33. Polysilicon springs 35 resilientlysuspend sensor layer 31 over the surface of wafer 33 providingresistance against acceleration forces. Deflection of the sensor layeris measured using a differential capacitor formed by independent fixedand central plates, the fixed plates driven by one hundred eightydegrees (180°) out of phase square waves having amplitude proportionalto acceleration. Signal outputs from each axis of sensor 25 areconditioned (i.e., phase sensitive demodulation and low pass filtering)and presented at analog output nodes. While not utilized in the primaryadvantageous embodiment of this invention, the ANALOG DEVICES'accelerometer is operable to convert the analog signals to duty cyclemodulated (“DCM”) signals at a DCM stage providing digital outputsignals capable of being directly counted at a processor.

While techniques for reconstructing analog signals from the digitaloutput signals may suitably be utilized (e.g., passing the duty cyclesignals though an RC filter), thereby allowing use of the digital signaloutput of a sensor of system 11 hereof, use of the analog signal outputshas been found advantageous due to the increased bandwidth availability(0.01 Hz to 5 kHz, adjustable at capacitors at the output nodes tobandlimit the nodes implementing low-pass filtering for antialiasing andnoise reduction), and the measuring sensitivity that may be attained. Atypical noise floor of five hundred micro “g” per Hertz (500×10⁻⁶“g”/Hz) is achieved, thereby allowing signals below five milli “g”(5×10⁻³ “g”) to be resolved for bandwidths below 60 Hz. The value “g” isthe acceleration of gravity at the surface of the earth (32 feet/sec² or9.8 m/sec²)

According to the illustrated embodiment, sensor 25 generates analogoutput voltage signals corresponding to measurements in the x and yaxes, which include both an alternating current (ac) voltage componentproportional to G forces (i.e., dynamic acceleration component relatedto vibrations of sensor layer 31) and a direct current (dc) voltagecomponent proportional to an angle relative to earth (i.e., staticacceleration component related to gravity). This open loop accelerationmeasurement architecture, capable of measuring both static and dynamicacceleration, can thus be utilized to determine position of a body bymeasuring both the x and y output voltages simultaneously, as well asmeasure forces of impact experienced by a body. This informationcomprises state indicia, and utilizing both signal components from bothoutputs, the sensed accelerative phenomena of the body may subsequentlybe processed to distinguish a variety of accelerative phenomena and,ultimately, to selectively act based on the distinctions, as isdescribed in detail hereafter to determine whether the evaluated bodymovement is normal or abnormal, and, if abnormal, whether the same iswithin tolerance.

It is noted that the foregoing embodiment has been introduced forillustrative purposes only. In alternate embodiments, any sensor that iscapable of sensing accelerative phenomena relative to a body may be usedin lieu of, or even in conjunction with, sensor 25. Further, alternateorientations of sensor 25 may be used for different applications.

Turning next to FIG. 2, there is illustrated a block diagram of theexemplary system of FIG. 1, which includes processing circuitry 39,indicating means 41, power supply 67, and switch 68, along with sensor25.

Exemplary processing circuitry 39 illustratively includes a processor 47and buffer amplifiers 43 and 45 that buffer the analog x and y outputsfrom sensor 25. Exemplary processor 47, which is associated with sensor25, is capable of processing the sensed accelerative phenomena as afunction of at least one accelerative event characteristic to therebydetermine whether an evaluated body movement is within environmentaltolerance. Processor 47 also preferably generates state indicia whileprocessing the sensed accelerative phenomena, which may represent thestate of the body within the environment over time. Processor 47 isassociated with a crystal oscillator/clock 49, switch (DIP) inputs 51,an analog-digital conversion circuitry 53 and a DSP filter 55 (oneconventional processor is available from TEXAS INSTRUMENTS, INC.,located in Dallas, Tex., United States of America, namely, Model No.MSP430P325).

Exemplary indicating means 41, in response to direction from processor47, is operable to accomplish at least one of the following: initiate analarm event; communicate such state, or tolerance, indicia to amonitoring controller; generate statistics; etc. Indicating means 41 maytake any number of forms, however, for use in system 11 of the presentembodiment, stage 41 is an RF transmitter including RF modulator 61enabled by processor 47. Exemplary data is presented and modulated atmodulator 61, amplified at amplifier 63 and transmitted at antenna 65(to a remote receiver unit as discussed hereinafter).

According to the present embodiment, power for the various components ofsystem 11 is provided by power supply 67, which illustratively is a 3.6volt lithium ion battery. Low power management may suitably be under thecontrol of processor 47 utilizing exemplary switched/power supplyvoltage FET switch 68 at sensor 25, which provides power only duringsampling cycles, and operates to shut components down during non-usecycles. For instance, processor 47 may be taken off-line when processingis complete, reducing current drain.

It should be noted that the various circuitry discussed heretofore hasbeen introduced herein for illustrative purposes only. System 11 may beimplemented using any suitably arranged computer or other processingsystem including micro, personal, mini, mainframe or super computers, aswell as network combinations of two or more of the same. In point offact, in one advantageous embodiment, sensor 25 and processor 47 are notco-located, but rather associated wirelessly. To that end, theprinciples of the present invention may be implemented in anyappropriately arranged device having processing circuitry. Processingcircuitry may include one or more conventional processors, programmablelogic devices, such as programmable array logic (“PALs”) andprogrammable logic arrays (“PLAs”), digital signal processors (“DSPs”),field programmable gate arrays (“FPGAs”), application specificintegrated circuits (“ASICs”), large scale integrated circuits(“ILSIs”), very large scale integrated circuits (“VLSIs”) or the like,to form the various types of circuitry, processors, controllers orsystems described and claimed herein.

Conventional computer system architecture is more fully discussed in THEINDISPENSABLE PC HARDWARE BOOK, by Hans-Peter Messmer, Addison Wesley(2nd ed. 1995) and COMPUTER ORGANIZATION AND ARCHITECTURE, by WilliamStallings, MacMillan Publishing Co. (3rd ed. 1993); conventionalcomputer, or communications, network design is more fully discussed inDATA NETWORK DESIGN, by Darren L. Spohn, McGraw-Hill, Inc. (1993);conventional data communications is more fully discussed in VOICE ANDDATA COMMUNICATIONS HANDBOOK, by Bud Bates and Donald Gregory,McGraw-Hill, Inc. (1996), DATA COMMUNICATIONS PRINCIPLES, by R. D.Gitlin, J. F. Hayes and S. B. Weinstein, Plenum Press (1992) and THEIRWIN HANDBOOK OF TELECOMMUNICATIONS, by James Harry Green, IrwinProfessional Publishing (2nd ed. 1992); and conventional circuit designis more fully discussed in THE ART OF ELECTRONICS, by Paul Horowitz andWinfield Hill, Cambridge University Press (2nd ed. 1991). Each of theforegoing publications is incorporated herein by reference for allpurposes.

Turning next to FIGS. 3A to 3D, illustrated are exemplary strip chartrecords of output of exemplary sensor 25 of FIGS. 1 and 2 taken duringillustrative situations. More particularly, FIGS. 3A and 3B illustratethe analog signal at the x and y outputs of sensor 25 during a fall by abody to the left, and whereas FIGS. 3C and 3D illustrate the analogsignal at the x and y outputs of sensor 25 during a fall by a body tothe right (the dark blocks indicating an alarm condition). As can beseen from the exemplary traces, a fall to the left and to the right areboth distinguishable by the disruption of a stable position, or normalbody movement, by a concussive force followed by a distinctly differentending stable position. According to the illustrative embodimentintroduced herein, the direction of fall is clear from the position ofthe ending trace at the y outputs. If the fall had been more forward orbackward, the x output traces would likewise clearly indicate the same(this assumes x and y sensor axes orientation as set forth in FIG. 1).Of course, the same x and y outputs of the sensor 25 may be suitablyprocessed to simply determine position of the body, for instance, suchas when a person-is lying down, when a box has tipped over, etc.

Turning next to FIG. 4, illustrated is operational flow diagram of anexemplary method (generally designated 400) of programming of processor47 in accordance with a fall detection application of the principles ofthe present invention. For the purposes of illustration, concurrentreference is made to system 11 of FIGS. 1 and 2. It should be noted thatthis illustration introduces an exemplary operational method forprogramming processor 47 for its use as a fall detector, and thatsuitable alternate embodiments of system 11 for evaluating movement of abody relative to different environments may likewise be implemented inaccordance with the principles hereof, such as for relative position,other assistance monitoring, transparent monitoring, tactical maneuvermonitoring, etc.

Exemplary method 400 begins and a request for sampling measurements isgenerated, likely by processor 47 (Step 405), either in response to anexecuting operations program or upon initiation by a user, possiblyremotely from a monitoring controller (discussed with reference to FIG.8). Sensor 25 senses x and y acceleration values generating measurementsignals at the outputs at sensor 25.

In the present implementation, the measurement signals are convertedfrom analog to digital format and filtered by filter 55 (Step 410;thereby reducing probability that an out-of-tolerance abnormal movementwill be determined incorrectly in response to a single sharp impact,such as a collision between mount 17 and a hard surface when sensor 25is off the body causing a sharp signal spike).

Processor 47 uses direct current (dc) voltage components of the outputsfrom sensor 25 to determine a last stable position of the body on whichsensor 25 is mounted (Step 415). More particularly, processor 47repeatedly compares successive input values with immediately precedinginput values and, if within tolerance, are added thereto and stored inan accumulator. This is repeated until Z samples have been accumulatedand added over some defined period of time (e.g., one second) or until areceived input is out of tolerance, in which case the sampling cycle isreinitiated. When Z samples are accumulated and added, the accumulatedvalue is divided by Z to determine a “last stable” static accelerationaverage value, which is saved and is indicative of the last stableposition of the body. Sampling and/or sampling cycle rates may bevaried, but, while preferably not continuous due to power consumptionconcerns, should be substantially continual. It is important to note,therefore, that such characteristics may be statically maintained ordynamically generated.

Processor 47 uses alternating current (ac) voltage components of eachoutput from sensor 25 to check against a G force threshold value set atDIP switch 51 to see if it exceeds the threshold (Step 420—thusqualifying as a potential fall impact, in the current example, possiblyan intensity in excess of about 2 to 4 G depending upon desiredsensitivity). According to the present implementation, if three of thesedynamic acceleration measurements are received in excess of thethreshold without five intervening measurements that are less than thethreshold, the impact detect flag may be set.

Processor 47 determines a fall by testing a post-impact stream ofsamples against a tolerance (Step 425; for instance, a selected value ofthe ac voltage components, for example a value less than about 2 G).Each new sample is tested against the previous sample to see if theposition of the body has stabilized. When the position has stabilized toless than the tolerance, W samples are averaged to get the new stablestatic acceleration average value corresponding to the new stableposition.

Processor 47, in response to the value corresponding to the new stableposition is shifted indicating a change of body position of 45° or morefrom the last stable position, classifies the event as a debilitatingfall and alert stage 41 is activated (Step 430). A greater stabilizationor post-stabilization sample period may be selected to allow more timefor an uninjured user to rise without issuance of an alert.

Processor 47, after setting the last stable position, adds the absolutevalues of the x and y last stable positions together, and, thendetermines whether the body associated with sensor 25 is lying down ifthe added value exceeds a value corresponding to 90° plus or minustwenty five percent (25%) (Step 435). In such case, after a selectedtime (for example, four seconds) with repeated like values, the layingdown detect flag is set. While this flag is set, any impact that exceedsthe G force threshold is treated as a debilitating fall (Step 440). Theflag is set only as long as the added value continues to indicate thatthe wearer is lying down.

It should be noted that the foregoing embodiment was introduced forillustrative purposes only and that the present invention broadlyintroduces systems, as well as methods of operating such systems, thatevaluate movement of a body relative to an environment, which in theabove-given example is an assistance monitoring environment. Animportant aspect of the present invention is that processor 47 isoperable to process sensed accelerative phenomena as a function of atleast one accelerative event characteristic, and that suchcharacteristics will largely be defined by the specific application.Therefore, system 11, and, more particularly, processor 47, generatesstate indicia relative the environment of interest, and determineswhether the evaluated body movement is within tolerance in the contextof that environment. For instance, “tolerance” would likely be verydifferent for a monitored body of an elderly person with a heartcondition, a toddler, a box in a freight car, a container of combustiblegas, etc.

Turning next to FIG. 5, illustrated is a functional block diagram of analternate sensing system (generally designated 71) that may suitably beassociated with processor 47 of FIGS. 1, 2, and 4 in accordance with theprinciples of the present invention. In this embodiment, componentsutilizable with system 11 are configured again as a human fallmonitor/detector, and any or all of these additional monitoringfunctions may be employed with system 11. For purposes of illustration,concurrent reference is made to processor 47 of FIGS. 2 and 4.

Exemplary sensor 71 includes a respiration module 73, which includes abody contact breath sensor 75 (for example a volumetric sensor, or anear body breath sensor), low pass filter 77 and amplifier 79 providingoutput signals indicative of respiration rate and vitality to processor47. The outputs are processed and, when a dangerous respiratorycondition is suggested (generates state indicia relative theenvironment, and determines whether the evaluated body movement (broadlydefined herein to include organic physiologic phenomena) is withinenvironmental tolerance), an identifiable (for example, by signalcoding) alarm is sent indicating means 41.

Sensor 71 further includes an ECG module 81, which includes inputelectrodes 83 and 85 providing heart rate signals to filters 87 and 89.The filtered signals are amplified at amplifier 91 and band passfiltered at filter 93. The output is amplified at 95 for input toprocessor 47 and processed so that dangerous heart rhythms and eventscan be detected (generates state indicia relative the environment, anddetermines whether the evaluated body movement is within environmentaltolerance) and an identifiable alarm sent at alert stage 41.

Sensor 71 further includes a panic button module 97 that is operableusing a standard user activated switch 99 positioned at housing 17allowing a user to initiate a call for help. The switch output is inputto processor 47 to initiate an identifiable alarm at alert stage 41.

Turning momentarily to FIGS. 6 and 7, illustrated are a perspective viewof an exemplary remote receiver unit of the system of this invention anda functional block diagram of the same. In a distributed system inaccord with one embodiment of this invention, a remote receiver unit 103(for example a wall mountable unit) as shown in FIGS. 6 and 7 isprovided for receipt of transmissions from sensor 25 and/or system 71.Unit 103 includes a receiver antenna 105, indicator LEDs 107 (includingindicators for as many detector functions as are employed in thespecific embodiment of the apparatus being monitored, as well as anindicator for unit on/off status), and a user interface input keypad 111for unit setup, reset and alarm deactivation. Power access 113 isprovided at the bottom of the unit.

RF receiver 115 is tuned to receive alarm transmissions from sensor 71and presents the signal received for processing at processor 117 foralarm identification and appropriate output. Processor 117 also receivesinputs from keypad 111 and power switch 119. Non-volatile memory 121 isprovided for input of identification of the user and/or of the apparatusbeing monitored. Audible alarm 123, LED bank 107 and retransmission unit125 (an autodialer, imbedded digital cellular technology, RFtransmitter, an Internet appliance, or the like) are connected toreceive outputs from processor 117.

When a transmission is received, or when battery power at the bodymounted apparatus is low, an audible alarm is sounded and theappropriate LED (indicative of the condition causing the alarm, forexample a debilitating fall by a user of apparatus 11) is activated. Ifnot disabled by the user at key pad 111 within a short period, processor117 activates retransmission unit 125 initiating a call for help orother remote notification.

Operational setup of unit 103 is also accomplished under programming atprocessor 117 and by sequential operation by a user or technician ofkeypad 111 and/or power switch 119 as is known (including user ID set,learn mode operations, reset or reprogramming operations, and urgencycode operations).

Turning next to FIG. 8, illustrated is an exemplary hybridwireless/wired network (generally designated 800) that is associatedwith a remote monitoring controller 805 according to one embodiment ofthe present invention. The wireless network 810 is introduced forillustrative purposes only, and comprises a plurality of cell sites 821to 823, each containing one of the base stations, BS 801, BS 802, or BS803. Base stations 801 to 803 are operable to communicate with aplurality of mobile stations (MS) including MS 103 (remote receiver unit103), and MS 811, MS 812 and MS 814. Mobile stations MS 103, and MS 811,MS 812 and MS 814, may be any suitable cellular devices, includingconventional cellular telephones, PCS handset devices, portablecomputers, metering devices, transceivers, and the like (including, forinstance, remote receiver unit 103).

Dotted lines show the approximate boundaries of the cell sites 821 to823 in which base stations 801 to 803 are located. The cell sites areshown approximately circular for the purposes of illustration andexplanation only. It should be clearly understood that the, cell sitesalso may have irregular shapes, depending on the cell configurationselected and natural and man-made obstructions.

In one embodiment of the present invention, BS 801, BS 802, and BS 803may comprise a base station controller (BSC) and a base transceiverstation (BTS). Base station controllers and base transceiver stationsare well known to those skilled in the art. A base station controller isa device that manages wireless communications resources, including thebase transceiver station, for specified cells within a wirelesscommunications network. A base transceiver station comprises the RFtransceivers, antennas, and other electrical equipment located in eachcell site. This equipment may include air conditioning units, heatingunits, electrical supplies, telephone line interfaces, and RFtransmitters and RF receivers, as well as call processing circuitry. Forthe purpose of simplicity and clarity in explaining the operation of thepresent invention, the base transceiver station in each of cells 821,822, and 823 and the base station controller associated with each basetransceiver station are collectively represented by BS 801, BS 802 andBS 803, respectively.

BS 801, BS 802 and BS 803 transfer voice and data signals between eachother and the public telephone system (not shown) via communicationsline 831 and mobile switching center (MSC) 840. Mobile switching center840 is well known to those skilled in the art. Mobile switching center840 is a switching device that provides services and coordinationbetween the subscribers in a wireless network and external networks 850,such as the Internet, public telephone system, etc. Communications line831 may be any suitable connection means, including a T1 line, a T3line, a fiber optic link, a network backbone connection, and the like.In some embodiments of the present invention, communications line 831may be several different data links, where each data link couples one ofBS 801, BS 802, or BS 803 to MSC 840.

In the exemplary wireless network 800, MS 811 is located in cell site821 and is in communication with BS 801, MS 103 is located in cell site822 and is in communication with BS 802, and MS 814 is located in cellsite 823 and is in communication with BS 803. MS 812 is also located incell site 821, close to the edge of cell site 823. The direction arrowproximate MS 812 indicates the movement of MS 812 towards cell site 823.

For the purposes of illustration, it is assumed that system 11 isassociated with an elderly person whose residence is wirelesslymonitored. It is further assumed that sensor 25 is associated with theelderly person and that processor 47 is coupled in MS/remote receiverunit 103, such that sensor 25 and processor 47 are wirelesslyassociated.

System 11 repeatedly senses various physiological phenomena of theelderly person, including accelerative phenomena of his body. Remoteprocessor 47 processes the repeatedly sensed phenomena, and,particularly, the accelerative phenomena of the body, as a function ofat least one accelerative event characteristic to thereby determinewhether the evaluated body movement is within environmental tolerance.Processor 47 advantageously generates state indicia while processing thesensed accelerative phenomena, representing the state of the body withinthe environment over time.

Exemplary processor 47 is programmed to distinguish between normal andabnormal accelerative events (e.g., walking, sitting, lying down, etc.versus tripping, falling down, etc.), and, when an abnormal event isidentified, indicates whether the abnormal event is tolerable, or withintolerance. Processor 47 may also suitably be programmed to distinguishother physical characteristics, including temperature, pressure, force,sound, light, relative position (including lying down), and the like.

As processor 47 generates state indicia, which includes toleranceindicia, it uses the same to determine whether the evaluated bodymovement is within environmental tolerance. Preferably, such toleranceindicia is compared with at least one threshold, likely associated withthe accelerative event characteristic. In response to such comparison,processor 47 controls a suitable indicating means to initiate an alarmevent (locally and via network 810 to monitoring controller 805), tocommunicate such tolerance indicia to a monitoring controller 805, togenerate statistics (locally and via network 810 to monitoringcontroller 805), or the like.

According to a related advantageous embodiment, such state indicia, andother information is communicated from time to time to monitoringcontroller 805, from which such information may suitably be perceived.For instance, a technician, medical professional, or relative might wishto review the activities and status of the elderly person. This mayeasily be facilitated via a centralized data repository accessible viathe Internet, or via any other suitably arranged network. While viewingsuch information, the technician, medical professional, or relative(subscriber 2, generally designated 855) might initiate a diagnosticequipment check, a physiological test, a simple status check, or thelike. Similarly, monitoring controller 805, via the network 800, maymonitor a “heartbeat” signal generated periodically by MS/remotereceiver unit 103, the heartbeat indicating that unit 103 is functional.

FIG. 9 is a schematic drawing of an alternate advantageous embodiment900 of the present invention. As shown in FIG. 9 sensor 25 of embodiment900 comprises three acceleration measuring devices 910, 920 and 930. Thenumber three is illustrative only. It is clear that sensor 25 comprisesa plurality of acceleration measuring devices and is not limited to aparticular number of acceleration measuring devices.

Acceleration measuring devices 910, 920 and 930 may each comprises aplural axis measuring device of the type previously described. Forconvenience, the acceleration measuring devices will be referred to asaccelerometers.

Accelerometers 910, 920 and 930 are each connected to controller 940.Controller 940 comprises processing circuitry 39 (including processor47), indicating means 41, power supply 67 and switch 68, of the typespreviously described.

As shown in FIG. 9, accelerometer 910, accelerometer 920, andaccelerometer 930 are each coupled directly to controller 940. As anelectrical circuit connection, it is said that accelerometer 910 andaccelerometer 920 are connected to controller 940 in an electricallyparallel connection. The connections of accelerometer 910 andaccelerometer 920 to controller 940 are not geometrically parallel toeach other. In at least one advantageous embodiment of the presentinvention the connections of accelerometer 910 and accelerometer 920 tocontroller 940 are located at right angles with respect to each other.The combination of accelerometer 920 and accelerometer 930 and thecombination of accelerometer 910 and accelerometer 930 are similarlyarranged.

In one arrangement of this advantageous embodiment of the presentinvention, accelerometer 910 is aligned parallel to the x-axis of athree dimensional Cartesian coordinated system and is capable ofmeasuring accelerations in the x direction. Accelerometer 920 is alignedparallel to the y-axis and is capable of measuring accelerations in they direction. Accelerometer 930 is aligned parallel to the z-axis and iscapable of measuring acceleration in the z direction.

Controller 940 is capable of simultaneously determining the values ofacceleration measured by each of accelerometers 910, 920 and 930. Inthis manner, controller 940 can determine the values of acceleration inx, y and z directions. Processor 47 in controller 940 is capable ofadding the values of acceleration in the x, y and z directions to obtaina vector sum (i.e., magnitude and direction) of the body (not shown) towhich accelerometers 910, 920 and 930 are attached. It is noted thatalthough embodiment 900 has been described for use with a threedimensional Cartesian coordinate system, other three dimensionalcoordinate systems may also be used.

For example, FIG. 10 illustrates a three dimensional spherical polarcoordinate system have coordinates R, Θ, Φ. FIG. 10 also illustrates therelationships between a Cartesian coordinate system superimposed on thespherical polar coordinate system. The coordinate R is radialcoordinate. The magnitude of R equals the distance from the origin ofthe coordinate system to the end of a vector that originates at theorigin. The coordinate Θ is an angular coordinate that measures theangle between the vector and the z axis. The coordinate Φ is measured inthe plane formed by the vector and the z axis. The coordinate Φ is anangular coordinate that measures the angle between the x axis and theprojection of the vector on the x-y plane. The coordinate Φ is measuredin the x-y plane.

As is shown in FIG. 10, the relationships between the Cartesiancoordinates and the spherical polar coordinates are given by:x=R sin Θ cos Φ  (1)y=R sin Θ sin Φ  (2)z=R cos Φ  (3)

The values of R, Θ, Φ may be calculated from the values x, y, z by theformulas:R=[x ² +y ² +z ²]^(1/2)   (4)Θ=tan⁻¹ [[[x ² +y ²]^(1/2) /z]  (5)Φ=tan⁻¹ [y/x]  (6)

As previously mentioned, a plurality of accelerometers may be used.Although each accelerometer 910, 920 and 930 is shown in FIG. 9 as asingle accelerometer, this arrangement is illustrative only. Eachaccelerometer 920, 920 and 930 may be replaced with two or moreaccelerometers (not shown). In other words, additional accelerometers(now shown) may be used in addition to accelerometers 910, 920 and 930shown in FIG. 9. The additional accelerometers may be oriented in anychosen direction and are not limited to being in the same plane as oneof the accelerometers 910, 920 and 930 (or in the same plane as one ofthe additional accelerometers). In general, accelerometers comprisingsensor 25 may be coupled in series, in parallel, or in a combination ofseries and parallel connections.

Accelerometer 910 is capable of generating analog output voltage signalscorresponding to measurements of acceleration in the x direction.Similarly, accelerometer 920 is capable of generating analog outputvoltage signals corresponding to measurements of acceleration in the ydirection and accelerometer 930 is capable of generating analog outputvoltage signals corresponding to measurements of acceleration in the zdirection.

The analog output voltage signals of accelerometer 910, 920 and 930 eachcomprise both an alternating current (ac) voltage component proportionalto G forces (i.e., dynamic acceleration component related to vibrationsof sensor layer 31 of sensor 25) and a direct current (dc) voltagecomponent proportional to an angle relative to earth (i.e., staticacceleration component related to gravity “g”).

The direct current (dc) voltage components from accelerometers 910, 920and 930 (representing static acceleration due to gravity in theirrespective x, y and z directions) may be combined to obtain a value ofthe acceleration that the body experiences due to gravity. In general,the vector R represents the resultant of combining the x, y and zcomponents of acceleration experienced by the body. When a body is atrest (i.e., dynamic acceleration is zero), the vector R represents thestatic acceleration due to gravity.

Because the value of gravity at the earth's surface is substantiallyconstant for any point on the surface of the earth, the value ofgravitational acceleration (obtained by vectorially summing thegravitational acceleration components) will be the same for eachmeasurement. That is, the vector sum of each set of gravitationalacceleration components will always give the same total value ofgravitational acceleration experienced by the body as long as the bodyis at rest relative to an inertial frame of reference. This value is thegravitational acceleration of approximately thirty two feet per secondper second (32 ft/sec²) or approximately nine and eight tenths metersper second per second (9.8 m/sec²). This value is customarily referredto as one “g.”

Processor 47 in controller 940 is capable of being programmed to soundan alarm condition when controller 940 receives signals fromaccelerometers 910, 920 and 930 that exceed an alarm limit set inaccordance with pre-programmed instructions. In this manner, controller940 can identify when the body to which accelerometers 910, 920 and 930have been coupled has experienced an acceleration that exceeds aspecified value.

Processor 47 is capable of combining the alternating current (ac)voltage components from accelerometers 910, 920 and 930 (representingdynamic acceleration due to external forces in their respective x, y andz directions) and the direct current (dc) voltage components fromaccelerometers 910, 920 and 930 (representing static acceleration due togravity in their respective x, y and z directions) to obtain a totalvalue of the acceleration that the body experiences (due to dynamicacceleration and due to gravity). Because the value of acceleration dueto gravity will always be equal to one “g”, any total value ofacceleration that exceeds one “g” will be caused by the presence ofdynamic acceleration on the body.

In an advantageous embodiment of the present invention, processor 47 isprogrammed to sound an alarm condition when controller 940 receivessignals from accelerometers 910, 920 and 930 that indicate that thetotal value of acceleration detected exceeds one “g.” In this manner,controller 940 determines that the body has experienced dynamicacceleration due to external forces because the measured accelerationhas exceeded the “background” acceleration reading that is alwayspresent from gravitational acceleration.

Controller 940 receives the total acceleration signal in the x directionfrom accelerometer 910, and the total acceleration signal in the ydirection from accelerometer 920, and the total acceleration signal inthe z direction from accelerometer 930. Controller 940 then combines thetotal acceleration components to obtain the total accelerationexperienced by the body. Controller 940 then subtracts the value of one“g” from the total acceleration. If the result is greater than zero,then controller 940 has determined that the body has experienced dynamicacceleration due to external forces. Controller 940 then sends an alarmsignal in the manner previously described.

In an alternate advantageous embodiment of the present invention, afirst plural axis accelerometer 910 and a second plural axisaccelerometer 920 are coupled to controller 940 in the orientationsshown in FIG. 11. Accelerometer 910 is aligned as shown in frame 1110.The first axis of accelerometer 910 is aligned parallel to the x axisand the second axis of accelerometer is aligned parallel to the y axis.Accelerometer 920 is aligned as shown in frame 1120. The first axis ofaccelerometer 920 is aligned parallel to the negative y axis and thesecond axis of accelerometer 920 is aligned parallel to the z axis.

An advantage is to be gained by aligning accelerometer 910 andaccelerometer 920 in this manner. When accelerometer 910 andaccelerometer 920 share a common axis it is possible to scale out anyinconsistencies between the readings of the two accelerometers. Forexample, assume that it is known that a force exists in the y direction.Then the force in the y direction will be the same for both of the twoaccelerometers. Assume that accelerometer 910 gives a reading of “1.0”for the y direction force and that accelerometer 920 gives a reading of“0.9” for the y direction force. If it is determined that accelerometer910 has the correct reading, then accelerometer 920 can be “scaled up”(i.e., corrected) to compensate for inconsistencies in the manufactureof accelerometer 920.

FIG. 12 illustrates an exemplary embodiment of the present invention inwhich accelerometer 910 and accelerometer 920 are coupled to controller940. Accelerometer 910 measures accelerations of the body in thepositive x direction and in the positive y direction. Accelerometer 920measures accelerations of the body in the negative y direction and inthe positive z direction.

The analog x signal from accelerometer 910 is coupled to an analogdigital converter (ADC) 1215 through filter 1205. Similarly, the analogy signal from accelerometer 910 is coupled to ADC 1215 through filter1210. Filter 1205 and filter 1210 filter out noise artifacts and cancelhigh frequency elements that may cause analog to digital aliasing.Filter 1205 and filter 1210 may be partially implemented using digitalsignal processing within controller 940.

ADC 1215 converts analog signals from filter 1205 and filter 1210 todigital signals. ADC 1215 may be external to controller 940 or may beincorporated within controller 940.

Similarly, the analog −y (i.e., negative y) signal from accelerometer920 is coupled to ADC 1215 through filter 1225. The analog z signal fromaccelerometer 920 is coupled to ADC 1215 through filter 1230. Filter1225 and filter 1230 also filter out noise artifacts and cancel highfrequency elements that may cause analog to digital aliasing. Filter1225 and filter 1230 may be partially implemented using digital signalprocessing within controller 940.

Controller 940 uses the x, y, z acceleration values to calculate valuesfor the x, y, z distances. This calculation is done by first calculatinga time integral of the x, y, z acceleration values to obtain x, y, zvelocity values. Then a time integral of the x, y, z velocity values iscalculated to obtain the x, y, z distance values. Controller 940 thenuses Equations (4), (5), and (6) to calculate the spherical polar (SP)coordinates R, Θ, Φ. Controller 940 then sends the digital form of theR, Θ, Φ coordinates to digital to analog converter (DAC) 1240. DAC 1240converts the digital form of the R, Θ, Φ coordinates into an analogform. DAC 1240 may be external to controller 940 or may be incorporatedwithin controller 940.

The analog R signal is filtered in filter 1250. The analog Θ signal isfiltered in filter 1260. The analog Φ signal is filtered in filter 1270.The filtered R, Θ, Φ signals are the spherical polar (SP) components ofa vector that represents a measurement of the location of the body towhich accelerometer 910 and accelerometer 920 are attached.

In one advantageous embodiment of the present invention, controller 940uses indicating means 41 to transmit the SP coordinates to RF receiver115 and processor 117 (as shown in FIG. 7). As previously mentioned, RFreceiver 115 is tuned to receive transmissions from indicating means 41.As will be more fully described, processor 117 is capable of analyzingthe SP coordinate information that it receives from controller 940.

As time passes, the body to which accelerometer 910 and accelerometer920 and controller 940 are attached moves (or does not move). Therefore,controller 940 continually sends to processor 117 a stream of SPcoordinates that represent the motion of the body. Memory 121 attachedto processor 117 contains a library of prerecorded sets of SPcoordinates in which each prerecorded set of SP coordinates represents atype of motion.

For example, a first prerecorded set of SP coordinates could representinactivity or the absence of motion (i.e., “no motion”). The absence ofmotion could signify the existence of a problem condition. If the bodyto which accelerometer 910 and accelerometer 920 and controller 940 isattached is a person, then a “no motion” signal could mean that (1) theperson has become unconscious and has ceased moving, or that (2) thesensor device has become detached from the person, or that (3) thesensor device has ceased to function properly.

A second prerecorded set of SP coordinates could represent a successfulattempt to change position. A third prerecorded set of SP coordinatescould represent an unsuccessful attempt to change position.

A fourth prerecorded set of SP coordinates could represent the motion ofa body moving with a particular type of gait, and especially a gait thatis associated with a disability (e.g., limping). The term “moving”generally refers to all types of motion such as walking, running,skipping, jogging, jumping, and other types of motion.

A fifth prerecorded set of SP coordinates could represent the motion ofa person who is unsteady and is swaying back and forth.

A sixth prerecorded set of SP coordinates could represent the motion ofa person who experiences a “near fall.” A near fall occurs when a personloses his or her balance but recovers in time to keep from actuallyfalling. A seventh prerecorded set of SP coordinates could represent themotion of a person who experiences an actual fall.

A series of different types of motion may be recorded in which each typeof motion is represented by a prerecorded set of SP coordinates.

Processor 117 analyzes the SP coordinate information that it receivesfrom controller 940 by comparing it with each prerecorded set of SPcoordinates stored in memory 121. When processor 117 identifies a matchbetween the measured set of SP coordinates from controller 940 and oneof the prerecorded sets of SP coordinates stored in memory 121, thenprocessor 117 generates and sends a message that a match has been found.

The message may be sent by audible alarm 123, LED bank 107 and/orretransmission unit 125. In this manner, controller 940 identifies typesof motions that the body experiences including, without limitation,falls, near falls and particular types of gaits of motion.

The ability of processor 117 to detect patterns of motion that typicallyprecede a fall is very useful in preventing falls. For example, anelderly or infirm person who attempts to rise from a bed or chair may besubject to falling. Assume that processor 117 detects a pattern ofmotion that typically occurs before a fall when a person is attemptingto rise from a bed or a chair. Processor 117 can then activate an alarmto alert the person that a fall may be imminent. Upon hearing the alarm,the person is warned to cease his or her attempt to rise. A nearbycaregiver may also hear the alarm and come to assist the person before afall occurs. In this manner serious falls can be prevented.

In an alternate advantageous embodiment of the present invention,controller 940 contains the library of prerecorded sets of SPcoordinates. In this embodiment, controller 940 performs the analysis ofthe SP coordinate data. When a match is found, controller 940 generatesand sends a message (using indicating means 41) that a match has beenfound. An alarm may then be sounded in the manner previously described.

FIG. 13 illustrates a flow diagram showing a first portion of anadvantageous embodiment of the method of the present invention. Thesteps of the first portion of the method are collectively referred towith the reference numeral 1300. At the start of the method,accelerometer 910 and accelerometer 920 measure the x, y, z values ofacceleration (step 1310). Controller 940 then calculates the x, y, zdistance values (step 1320). Controller 940 then converts the x, y, zdistance values to spherical polar (SP) coordinates (step 1330).

Processor 117 (or controller 940 in an alternative embodiment) comparesa measured set of SP coordinates with each of the plurality ofprerecorded sets of SP coordinates that represents a type of motion(step 1340). Processor 117 (or controller 940 in an alternativeembodiment) identifies a match between the measured set of SPcoordinates and one particular prerecorded set of SP coordinates thatrepresents a type of motion (step 1350). Processor 117 (or controller940 in an alternative embodiment) then sends a message that a match hasbeen found (step 1360).

FIG. 14 illustrates a flow diagram showing a second portion of anadvantageous embodiment of the method of the present invention. Thesteps of the second portion of the method are collectively referred towith the reference numeral 1400.

The second portion of the method uses the SP coordinate data tocalculate a value for a static acceleration vector that represents thevalue of the earth's gravitational acceleration. When an object falls ina vacuum (i.e., an environment where there is no frictional force due toair resistance) the sum of the components for the static accelerationvector is zero.

When a person loses his or her balance and falls, the measurement of thestatic acceleration vector that controller 940 records is not zero. Themeasured value is less than one “g” but is greater than a zero value.The value is greater than zero because the person's muscle tone (due tothe slight contraction of skeletal muscles that is always present)operates to slow the person's body a little bit as the body falls. Insome cases, objects may impede the person's fall or the person mayreflexively grasp some object to slow the rate of fall.

When the value of the static acceleration vector reaches a value that isless than one “g” but greater than a zero value, that is an indicationthat controller 940 has experienced a fall. Unlike some types of priorart methods (e.g., tilt switches), this method of detecting a fall doesnot rely on detecting a change in the angle of orientation of the body.The occurrence of a fall is detected by detecting a reduction in thevalue of the static acceleration vector to a value that is less than one“g.”

If controller 940 was not connected to a person's body during the fall,then the value of the static acceleration vector measured by controller940 after the fall will instantaneously be equal to one “g.” Ifcontroller 940 was connected to a person's body during the fall, thenthe value of the static acceleration vector measured by controller 940after the fall will, rise relatively slowly. This is due to the factthat the person's muscle tone (due to the slight contraction of skeletalmuscles that is always present) operates to slow the rise of the valueof the static acceleration vector after the fall.

If the value of the static acceleration vector rises at a rate that isgreater than a preselected threshold rate, then it is clear thatcontroller 940 was not connected to a person's body during the fall. Ifthe value of the static acceleration vector rises at a rate that is lessthan a predetermined threshold rate, then it is clear that controller940 was connected to a person's body during the fall.

At the start of the second portion of the method of the presentinvention, controller 940 has converted the x, y, z distance values tospherical polar (SP) coordinates (step 1330). Controller 940 then usesthe SP coordinates to calculate the value of the static accelerationvector (step 1410). Controller 940 determines whether the value of thestatic acceleration vector has reached a value that is less than one “g”(decision step 1420). If not, then controller 940 updates the SPcoordinates (step 1430) and control returns to step 1410.

If the value of the static acceleration vector has reached a value thatis less than one “g,” then controller 940 determines the rate at whichthe value of the static acceleration vector is increasing from the valuethat is less than one “g” (step 1440). Processor 940 then compares therate to a preselected threshold rate (decision step 1450). If the rateis greater than the preselected threshold rate, then controller 940sends a message that controller 940 was not connected to the person'sbody during the fall (step 1470). If the rate is not greater than thepreselected threshold rate, then controller 940 sends a message thatcontroller 940 was connected to the person's body during the fall (step1460). In this manner controller 940 is able to distinguish between afall of controller 940 alone and a fall of controller 940 whilecontroller 940 was coupled to a person's body.

Relatively rare instances may occur in which controller 940 will requireadditional information to distinguish between a fall of controller 940alone and a fall of controller 940 while controller 940 is coupled to aperson's body. As previously described, the measured value ofacceleration of a falling person is usually less than one “g” but isgreater than a zero value. The value is greater than zero because theperson's muscle tone (due to the slight contraction of skeletal musclesthat is always present) operates to slow the person's body a little bitas the body falls. This is true for normal falling situations.

However, it is not true in the relatively rare cases in which thefalling person's body is not in contact with any object. For example, ifa person falls off a ladder, then the person's body falls through theatmosphere and does not make contact with any object until impact withthe floor or ground. In this type of fall the falling person's muscletone does not operate to slow the person's body during the fall becausethe person is not in contact with an external object.

An alternate advantageous embodiment of the present invention can detectthis type of fall. In the alternate embodiment controller 940 detects anadditional signal to determine whether controller 940 was coupled to thefalling person's body. For example, as previously described, controller940 comprises processing circuitry 39 that is capable of receiving asignal from respiration module 73. Respiration module 73 is capable ofdetecting the respiration rate of the falling person.

In an alternate embodiment of the present invention, controller 940detects a rate at which the value of the static acceleration vector isincreasing from a value that is less than one “g”. If the detected rateis greater than a preselected threshold rate (usually indicative of afall of controller 940 not coupled to a body), then controller 940determines whether a respiration signal was detected within apredetermined time period (e.g., six (6) seconds). If a respirationsignal was detected, then processor 940 reports that the fall was a fallof controller 940 connected to a body and not a fall of controller 940alone.

Although the present invention has been described in detail, thoseskilled in the art should understand that they can make various changes,substitutions and alterations herein without departing from the spiritand scope of the invention in its broadest form.

1. A system that evaluates movement of a body relative to anenvironment, said system comprising: a sensor, associable with saidbody, that senses accelerative phenomena of said body relative to athree dimensional frame of reference in said environment, said sensorcomprising a plurality of acceleration measuring devices; and aprocessor, associated with said sensor, that processes said sensedaccelerative phenomena of said body as a function of at least oneaccelerative event characteristic to thereby determine whether saidevaluated body movement is within an environmental tolerance, and tothereby determine whether said body has experienced acceleration thatrepresents one of a plurality of different types of motion.
 2. Thesystem set forth in claim 1 wherein said one of said plurality ofdifferent types of motion is one of: no motion, a successful attempt tochange position, an unsuccessful attempt to change position, a motion ofa body moving with a gait, a motion of a body moving with a gaitassociated with a disability, a swaying motion, a near fall, and a fall.3. The system set forth in claim 1 wherein said plurality ofacceleration measuring devices comprises three accelerometers in whicheach accelerometer is aligned along one axis of a three dimensionalcoordinate system.
 4. The system set forth in claim 1 wherein saidplurality of acceleration measuring devices comprises two plural axisaccelerometers in which a first plural axis accelerometer is alignedwithin a first plane of a three dimensional coordinate system and inwhich a second plural axis accelerometer is aligned within a secondplane of said three dimensional coordinate system.
 5. The system setforth in claim 4 comprising a controller containing said processor, saidcontroller capable of receiving from said two plural axis accelerometersvalues of acceleration of body motion measured in an x direction, in a ydirection, and in a z direction.
 6. The system set forth in claim 5wherein said controller is capable of using said values of accelerationof body motion measured in said x, y, z directions to calculate valuesfor x, y, z distance components of body motion.
 7. The system set forthin claim 6 wherein said controller is capable of using said x, y, zdistance components of body motion to calculate equivalent sphericalpolar coordinate components of body motion.
 8. The system set forth inclaim 7 wherein said controller is capable of comparing a set ofspherical polar coordinate components that represents a measurement ofsaid body motion to each of a plurality of prerecorded sets of sphericalpolar coordinate components in which each set of said plurality of setsof spherical polar coordinate components represents a type of motion. 9.The system set forth in claim 8 wherein one of said plurality ofprerecorded sets of spherical polar coordinate components represents oneof: no motion, a successful attempt to change position, an unsuccessfulattempt to change position, a motion of body moving with a gait, amotion of a body moving with a gait associated with a disability, aswaying motion, a near fall, and a fall.
 10. The system set forth inclaim 8 wherein said controller is capable of identifying a matchbetween said set of spherical polar coordinate components thatrepresents a measurement of said body motion with one of a plurality ofsaid prerecorded sets of spherical polar coordinate components toidentify a type of motion that corresponds to said body motion.
 11. Thesystem set forth in claim 10 wherein after identifying said type ofmotion said controller sends an alarm signal indicative of said type ofmotion.
 12. The system set forth in claim 11 wherein said alarm signalis communicated via a network to a monitoring controller.
 13. The systemset forth in claim 12 wherein said network is a wireless network. 14.The system set forth in claim 11 wherein said body is a person andwherein said controller sends signals representing physiological data ofsaid person together with said alarm signal.
 15. The system set forth inclaim 14 wherein said alarm signal and said signals representingphysiological data of said person are communicated via a network to amonitoring controller.
 16. The system set forth in claim 15 wherein saidnetwork is a wireless network.
 17. The system set forth in claim 7wherein said controller is capable of calculating a value of a staticacceleration vector from said spherical polar coordinate components ofsaid body motion.
 18. The system set forth in claim 17 wherein saidcontroller is capable of determining when said value of said staticacceleration vector reaches a value less than the acceleration ofgravity indicative of a fall.
 19. The system set forth in claim 18wherein said controller is capable of determining a rate at which saidvalue of said static acceleration vector increases after the value ofsaid static acceleration vector has reached a value less than theacceleration of gravity indicative of a fall.
 20. The system set forthin claim 19 wherein said controller is capable of using said rate ofincrease of said value of said static acceleration vector to determinewhether said controller was connected to a body during a fall thatcaused the value of said static acceleration vector to reach a valueless than the acceleration of gravity.
 21. A method of operating asystem to evaluate movement of a body relative an environment wherein asensor is associated with said body, said method of operation comprisingthe steps of: processing, with a processor, repeatedly sensedaccelerative phenomena of said body as a function of at least oneaccelerative event characteristic to thereby determine whether saidevaluated body movement is within environmental tolerance; anddetermining whether said body has experienced acceleration thatrepresents one of a plurality of different types of motion.
 22. Themethod set forth in claim 21 wherein one of said plurality of differenttypes of motion is one of: no motion, a successful attempt to changeposition, an unsuccessful attempt to change position, a motion of a bodymoving with a gait, a motion of a body moving with a gait associatedwith a disability, a swaying motion, a near fall, and a fall.
 23. Themethod set forth in claim 21 further comprising the steps of: receivingin a controller comprising said processor a value of acceleration ofbody motion in an x direction and in a y direction from a first pluralaxis accelerometer aligned within a first plane of a three dimensionalcoordinate system; and receiving in said controller a value ofacceleration of body motion in a y direction and in a z direction from asecond plural axis accelerometer aligned within a second plane of saidthree dimensional coordinate system.
 24. The method set forth in claim23 further comprises the step of: calculating in said controller valuesfor x, y, z distance components of body motion using said values ofacceleration of body motion measured in x, y, z directions.
 25. Themethod set forth in claim 24 further comprising the step of: calculatingin said controller spherical polar coordinate components of said bodymotion that are equivalent to said x, y, z distance components of saidbody motion.
 26. The method set forth in claim 25 further comprising thesteps of: comparing a set of spherical polar coordinate components thatrepresents a measurement of said body motion to each of a plurality ofprerecorded sets of spherical polar coordinate components in which eachset of said plurality of sets of spherical polar coordinate componentsrepresents a type of motion; and identifying a match between said set ofspherical polar coordinate components that represents a measurement ofsaid body motion with one of said plurality of said prerecorded sets ofspherical polar coordinate components; and identifying a type of motionthat corresponds to said body motion.
 27. The method set forth in claim26 wherein one of said plurality of said prerecorded sets of sphericalpolar coordinate components represents one of: no motion, a successfulattempt to change position, an unsuccessful attempt to change position,a motion of body moving with a gait, a motion of a body moving with agait associated with a disability, a swaying motion, a near fall, and afall.
 28. The method set forth in claim 27 further comprising the stepof: sending an alarm signal indicative of said type of motion after saidcontroller identifies said type of motion.
 29. The method set forth inclaim 28 further comprising the step of; sending said alarm signal via anetwork to a monitoring controller.
 30. The method set forth in claim 29wherein said network is a wireless network.
 31. The method set forth inclaim 28 wherein said body is a person and further comprising the stepsof: sending signals representing physiological data of said persontogether with said alarm signal.
 32. The method set forth in claim 31further comprising the step of: sending signals representingphysiological data of said person via a network to a monitoringcontroller.
 33. The method set forth in claim 32 wherein said network isa wireless network.
 34. The method set forth in claim 25 furthercomprising the step of: calculating in said controller a value of astatic acceleration vector using said spherical polar coordinatecomponents of said body motion.
 35. The method set forth in claim 34further comprising the step of: determining in said controller when saidvalue of said static acceleration vector reaches a value less than theacceleration of gravity indicative of a fall.
 36. The method set forthin claim 35 further comprising the step of: determining in saidcontroller a rate at which said value of said static acceleration vectorincreases after the value of said static acceleration vector has reacheda value less than the acceleration of gravity indicative of a fall. 37.The method set forth in claim 36 further comprising the step of:determining with said rate whether said controller was connected to saidbody during said fall that caused the value of said static accelerationvector to reach a value less than the acceleration of gravity.
 38. Themethod set forth in claim 37 further comprising the step of: receivingin said controller a signal that detects a physiological function ofsaid body within a time period, said signal indicating that saidcontroller was connected to said body during said fall that caused thevalue of said static acceleration vector to reach a value less than theacceleration of gravity.